The objective of this study was to determine the extent to which the compensatory nutrition regimen modulates lactation performance and milk protein gene expression in the first and second lactation cycles. Female rats(28 days of age) were assigned to 1)control ad libitum ; 2) stari-step compensatory nutrition(SSCN) regimen an alternating 3-2-3-4-week schedule beginning with an energy restriction diet(40% restriction) for 3 weeks followed by the control diet(ad libitum) for 2 weeks and then alternating another 3-4 week feeding regimen. The SSCN rats were received an overall 20% energy restriction(average from all stair-step periods) compared with the conventionally fed control group. Rats were bred during the first week of the second realimentation. All pups were weaned on day 21 of lactation. About 1 week after weaning all dams were mated for the second pregnancy. Mammary tissues were obtained from pregnant and lactating rats during the first and second lactation cycles. During these lactation cycles the SSCN group had a 11% increase in average lactation performance over that of control. The SSCN group had significantly increased levels of milk protein gene($alpha$- and $eta$-casein) expression in mammary tissues during the first lactation cycle compared with those of the control group. During the second lactation period the levels of milk protein gene expression in lactating mammary tissues of the SSCN group were also higher than those of the control group. These results suggest that the effects of compensatory growth imposed at an early age extend to the second lactation cycle with regard to increased lactation performance and milk protein gene expression